High-strength, corrosion resistant aluminum alloys for use as fin stock and methods of making the same

ABSTRACT

Disclosed herein are high-strength, highly formable, and corrosion resistant aluminum alloys, methods of making and processing such alloys, and products prepared from such alloys. More particularly, disclosed are novel aluminum alloys exhibiting improved mechanical strength, formability, and corrosion resistance. The alloys can be used as fin stock in industrial applications, including in heat exchangers.

FIELD

This disclosure relates to the fields of material science, materialchemistry, metallurgy, aluminum alloys, aluminum fabrication, andrelated fields. More specifically, the disclosure provides novelaluminum alloys that can be used in a variety of applications,including, for example, as a fin stock for a heat exchanger.

BACKGROUND

Heat exchangers are widely used in various applications, including, butnot limited to, heating and cooling systems in various industrial andchemical processes. Many of these configurations utilize fins inthermally conductive contact with the outside of tubes to provideincreased surface area across which heat can be transferred between thefluids. In addition, fins are used to regulate flow of fluids throughthe heat exchanger. However, aluminum alloy heat exchangers have arelatively high susceptibility to corrosion. Corrosion eventually leadsto loss of refrigerant from the tubes and failure of the heating orcooling system. High strength, corrosion resistant alloys are desirablefor improved product performance. However, identifying alloycompositions and processing conditions that will provide such an alloythat addresses these failures has proven to be a challenge.

Heat exchanger tubes can be made from copper or an aluminum alloy andheat exchanger fins can be made from a different aluminum alloy (e.g.,AA1100 or AA7072). The fins can be fitted over copper or aluminum tubesand mechanically assembled. Larger heating, ventilation, airconditioning and refrigeration (HVAC&R) units can require longer finsand it is important they have sufficient strength for downstreamprocessing (e.g., handling and/or forming into coils). One method tomaintain strength of the fins is to provide thicker gauge fins; however,this can increase cost and add weight.

SUMMARY

Covered embodiments of the invention are defined by the claims, not thissummary. This summary is a high-level overview of various aspects of theinvention and introduces some of the concepts that are further describedin the Detailed Description section below. This summary is not intendedto identify key or essential features of the claimed subject matter, noris it intended to be used in isolation to determine the scope of theclaimed subject matter. The subject matter should be understood byreference to appropriate portions of the entire specification, any orall drawings and each claim.

Provided herein are novel aluminum alloys that exhibit high strength andcorrosion resistance. The aluminum alloys described herein compriseabout 0.7-3.0 wt. % Zn, about 0.15-0.35 wt. % Si, about 0.25-0.65 wt. %Fe, about 0.05-0.20 wt. % Cu, about 0.75-1.50 wt. % Mn, about 0.50-1.50wt. % Mg, up to about 0.05 wt. % Cr, up to about 0.05 wt. % Ti, and upto about 0.15 wt. % of impurities, with the remainder as Al. In someexamples, the aluminum alloy comprises about 1.0-2.5 wt. % Zn, about0.2-0.35 wt. % Si, about 0.35-0.60 wt. % Fe, about 0.10-0.20 wt. % Cu,about 0.75-1.25 wt. % Mn, about 0.90-1.30 wt. % Mg, up to about 0.05 wt.% Cr, up to about 0.05 wt. % Ti, and up to about 0.15 wt. % ofimpurities, with the remainder as Al. In some examples, the aluminumalloy comprises about 1.5-2.5 wt. % Zn, about 0.17-0.33 wt. % Si, about0.30-0.55 wt. % Fe, about 0.15-0.20 wt. % Cu, about 0.80-1.00 wt. % Mn,about 1.00-1.25 wt. % Mg, up to about 0.05 wt. % Cr, up to about 0.05wt. % Ti, and up to about 0.15 wt. % of impurities, with the remainderas Al. Optionally, the aluminum alloy comprises about 0.9-2.6 wt. % Zn,about 0.2-0.33 wt. % Si, about 0.49-0.6 wt. % Fe, about 0.15-0.19 wt. %Cu, about 0.79-0.94 wt. % Mn, about 1.13-1.27 wt. % Mg, up to about 0.05wt. % Cr, up to about 0.05 wt. % Ti, and up to about 0.15 wt. % ofimpurities, with the remainder as Al. Optionally, the aluminum alloycomprises about 1.4-1.6 wt. % Zn, about 0.2-0.33 wt. % Si, about0.49-0.6 wt. % Fe, about 0.15-0.19 wt. % Cu, about 0.79-0.94 wt. % Mn,about 1.13-1.27 wt. % Mg, up to about 0.05 wt. % Cr, up to about 0.05wt. % Ti, and up to about 0.15 wt. % of impurities, with the remainderas Al. The alloy can be produced by casting (e.g., direct chill castingor continuous casting), homogenization, hot rolling, cold rolling,and/or annealing. The alloy can be in an H temper or an O temper.

The yield strength of the alloy is at least about 70 MPa. The ultimatetensile strength of the alloy can be at least about 170 MPa. Thealuminum alloy can comprise an electrical conductivity above about 37%based on the international annealed copper standard (IACS). Optionally,the aluminum alloy comprises a corrosion potential of from about −740 mVto −850 mV.

Also provided herein are products comprising the aluminum alloy asdescribed herein. The products can include a fin stock. Optionally, thegauge of the fin stock is 1.0 mm or less (e.g., 0.15 mm or less).Further provided herein are articles comprising a tube and a fin,wherein the fin comprises the fin stock as described herein.

Further provided herein are methods of producing a metal product. Themethods include the steps of casting an aluminum alloy as describedherein to form a cast aluminum alloy, homogenizing the cast aluminumalloy, hot rolling the cast aluminum alloy to produce a rolled product,and cold rolling the rolled product to a final gauge product.Optionally, the methods further include a step of annealing the finalgauge product. Products (e.g., heat exchanger fins) obtained accordingto the methods are also provided herein.

Further aspects, objects, and advantages will become apparent uponconsideration of the detailed description of non-limiting examples thatfollow.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 contains digital images of exemplary alloys described hereincoupled with a comparative alloy described herein and subjected tocorrosion testing for various time periods.

FIG. 2 contains digital images of exemplary alloys described hereincoupled with a comparative alloy described herein and subjected tocorrosion testing for various time periods.

DETAILED DESCRIPTION

Described herein are high-strength, corrosion resistant aluminum alloysand methods of making and processing the same. The aluminum alloysdescribed herein exhibit improved mechanical strength, corrosionresistance, and/or formability. The alloys provided herein include azinc constituent and can be especially useful as a sacrificial alloy(e.g., as fin stock material for use in combination with copper oraluminum alloy tubes in heat exchangers). The disclosed alloycomposition provides a material having mechanical strength as well assacrificial alloy characteristics. The alloy material can be formed asfin stock and attached mechanically to copper or aluminum alloy tubing.The fin stock can sacrificially corrode, thus protecting the copper oraluminum alloy tubing from corrosion. Additionally, the aluminum alloyfin stock described herein has excellent mechanical strength providingthinner gauge aluminum alloy fin stock. The alloys can be used as finstock in industrial applications, including in heat exchangers, or inother applications. In a heat exchanger, the alloys serve as asacrificial component, ensuring the protection of other components ofthe heat exchanger (e.g., a tube to which the alloy is attached).

Definitions and Descriptions

The terms “invention,” “the invention,” “this invention,” and “thepresent invention” used herein are intended to refer broadly to all ofthe subject matter of this patent application and the claims below.Statements containing these terms should be understood not to limit thesubject matter described herein or to limit the meaning or scope of thepatent claims below.

In this description, reference is made to alloys identified by aluminumindustry designations, such as “series” or “1xxx.” For an understandingof the number designation system most commonly used in naming andidentifying aluminum and its alloys, see “International AlloyDesignations and Chemical Composition Limits for Wrought Aluminum andWrought Aluminum Alloys” or “Registration Record of Aluminum AssociationAlloy Designations and Chemical Compositions Limits for Aluminum Alloysin the Form of Castings and Ingot,” both published by The AluminumAssociation.

As used herein, the meaning of “a,” “an,” or “the” includes singular andplural references unless the context clearly dictates otherwise.

As used herein, a plate generally has a thickness of greater than about15 mm. For example, a plate may refer to an aluminum product having athickness of greater than about 15 mm, greater than about 20 mm, greaterthan about 25 mm, greater than about 30 mm, greater than about 35 mm,greater than about 40 mm, greater than about 45 mm, greater than about50 mm, or greater than about 100 mm.

As used herein, a shate (also referred to as a sheet plate) generallyhas a thickness of from about 4 mm to about 15 mm. For example, a shatemay have a thickness of about 4 mm, about 5 mm, about 6 mm, about 7 mm,about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13mm, about 14 mm, or about 15 mm.

As used herein, a sheet generally refers to an aluminum product having athickness of less than about 4 mm. For example, a sheet may have athickness of less than about 4 mm, less than about 3 mm, less than about2 mm, less than about 1 mm, less than about 0.5 mm, less than about 0.3mm, or less than about 0.1 mm.

Reference is made in this application to alloy temper or condition. Foran understanding of the alloy temper descriptions most commonly used,see “American National Standards (ANSI) H35 on Alloy and TemperDesignation Systems.” An F condition or temper refers to an aluminumalloy as fabricated. An O condition or temper refers to an aluminumalloy after annealing. An Hxx condition or temper, also referred toherein as an H temper, refers to an aluminum alloy after cold rollingwith or without thermal treatment (e.g., annealing). Suitable H tempersinclude HX1, HX2, HX3 HX4, HX5, HX6, HX7, HX8, or HX9 tempers. Forexample, the aluminum alloy can be cold rolled only to result in apossible H19 temper. In a further example, the aluminum alloy can becold rolled and annealed to result in a possible H23 temper.

The following aluminum alloys are described in terms of their elementalcomposition in weight percentage (wt. %) based on the total weight ofthe alloy. In certain examples of each alloy, the remainder is aluminum,with a maximum wt. % of 0.15% for the sum of the impurities.

As used herein, “electrochemical potential” refers to a material'samenability to a redox reaction. Electrochemical potential can beemployed to evaluate resistance to corrosion of aluminum alloysdescribed herein. A negative value can describe a material that iseasier to oxidize (e.g., lose electrons or increase in oxidation state)when compared to a material with a positive electrochemical potential. Apositive value can describe a material that is easier to reduce (e.g.,gain electrons or decrease in oxidation state) when compared to amaterial with a negative electrochemical potential. Electrochemicalpotential, as used herein, is a vector quantity expressing magnitude anddirection.

As used herein, the meaning of “room temperature” can include atemperature of from about 15° C. to about 30° C., for example about 15°C., about 16° C., about 17° C., about 18° C., about 19° C., about 20°C., about 21° C., about 22° C., about 23° C., about 24° C., about 25°C., about 26° C., about 27° C., about 28° C., about 29° C., or about 30°C. All ranges disclosed herein are to be understood to encompass any andall subranges subsumed therein. For example, a stated range of “1 to 10”should be considered to include any and all subranges between (andinclusive of) the minimum value of 1 and the maximum value of 10; thatis, all subranges beginning with a minimum value of 1 or more, e.g., 1to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.

Alloy Compositions

Described below are novel aluminum alloys. In certain aspects, thealloys exhibit high strength, corrosion resistance, and/or highformability. The properties of the alloys are achieved due to theelemental compositions of the alloys as well as the methods ofprocessing the alloys to produce the described sheets, plates, andshates. Specifically, increased zinc (Zn) content provides alloys thatpreferentially corrode when attached to copper or other aluminum alloytubes, thus providing cathodic protection to the tubes. Surprisingly, Znaddition has exhibited additional solute strengthening in addition tothe strengthening effect of increased magnesium (Mg) content.Additionally, an optimum Zn content has been observed. In some examples,additions of Zn of greater than about 2.0 wt. % are not desirable, assuch amounts can have a detrimental effect on conductivity andself-corrosion rates. However, in some examples, it may be desirable tosacrifice those conductivity and corrosive properties to allow forsufficient cathodic protection of the tube. To this end, a maximum Zncontent of up to about 3.0 wt. % can be used to provide the desiredcorrosion, conductivity, and strength properties.

The alloys and methods described herein can be used in industrialapplications including sacrificial parts, heat dissipation, packaging,and building materials. The alloys described herein can be employed asindustrial fin stock for heat exchangers. The industrial fin stock canbe provided such that it is more resistant to corrosion than currentlyemployed industrial fin stock alloys (e.g., AA7072 and AA1100) and willstill preferentially corrode, protecting other metal parts incorporatedin a heat exchanger.

In some examples, the alloys can have the following elementalcomposition as provided in Table 1.

TABLE 1 Element Weight Percentage (wt. %) Zn 0.7-3.0 Si 0.15-0.35 Fe0.25-0.65 Cu 0.05-0.20 Mn 0.75-1.50 Mg 0.50-1.50 Cr 0.00-0.10 Ti0.00-0.10 Others 0-0.05 (each) 0-0.15 (total) Al Remainder

In some examples, the alloys can have the following elementalcomposition as provided in Table 2.

TABLE 2 Element Weight Percentage (wt. %) Zn 1.0-2.5 Si  0.2-0.35 Fe0.35-0.60 Cu 0.10-0.20 Mn 0.75-1.25 Mg 0.90-1.30 Cr 0.00-0.05 Ti0.00-0.05 Others 0-0.05 (each) 0-0.15 (total) Al Remainder

In some examples, the alloys can have the following elementalcomposition as provided in Table 3.

TABLE 3 Element Weight Percentage (wt. %) Zn 1.5-2.5 Si 0.17-0.33 Fe0.30-0.55 Cu 0.15-0.20 Mn 0.80-1.00 Mg 1.00-1.25 Cr 0.00-0.05 Ti0.00-0.05 Others 0-0.05 (each) 0-0.15 (total) Al Remainder

In some examples, the alloys can have the following elementalcomposition as provided in Table 4.

TABLE 4 Element Weight Percentage (wt. %) Zn 0.9-2.6 Si  0.2-0.33 Fe0.49-0.6  Cu 0.15-0.19 Mn 0.79-0.94 Mg 1.13-1.27 Cr 0.00-0.05 Ti0.00-0.05 Others 0-0.05 (each) 0-0.15 (total) Al Remainder

In some examples, the alloy includes zinc (Zn) in an amount from about0.7% to about 3.0% (e.g., from about 1.0% to about 2.5%, from about 1.5%to about 3.0%, from about 0.9% to about 2.6%, or from about 1.4% toabout 1.6%) based on the total weight of the alloy. For example, thealloy can include about 0.7%, about 0.71%, about 0.72%, about 0.73%,about 0.74%, about 0.75%, about 0.76%, about 0.77%, about 0.78%, about0.79%, about 0.8%, about 0.81%, about 0.82%, about 0.83%, about 0.84%,about 0.85%, about 0.86%, about 0.87%, about 0.88%, about 0.89%, about0.9%, about 0.91%, about 0.92%, about 0.93%, about 0.94%, about 0.95%,about 0.96%, about 0.97%, about 0.98%, about 0.99%, about 1.0%, about1.01%, about 1.02%, about 1.03%, about 1.04%, about 1.05%, about 1.06%,about 1.07%, about 1.08%, about 1.09%, about 1.1%, about 1.11%, about1.12%, about 1.13%, about 1.14%, about 1.15%, about 1.16%, about 1.17%,about 1.18%, about 1.19%, about 1.2%, about 1.21%, about 1.22%, about1.23%, about 1.24%, about 1.25%, about 1.26%, about 1.27%, about 1.28%,about 1.29%, about 1.3%, about 1.31%, about 1.32%, about 1.33%, about1.34%, about 1.35%, about 1.36%, about 1.37%, about 1.38%, about 1.39%,about 1.4%, about 1.41%, about 1.42%, about 1.43%, about 1.44%, about1.45%, about 1.46%, about 1.47%, about 1.48%, about 1.49%, about 1.5%,about 1.51%, about 1.52%, about 1.53%, about 1.54%, about 1.55%, about1.56%, about 1.57%, about 1.58%, about 1.59%, about 1.6%, about 1.61%,about 1.62%, about 1.63%, about 1.64%, about 1.65%, about 1.66%, about1.67%, about 1.68%, about 1.69%, about 1.7%, about 1.71%, about 1.72%,about 1.73%, about 1.74%, about 1.75%, about 1.76%, about 1.77%, about1.78%, about 1.79%, about 1.8%, about 1.81%, about 1.82%, about 1.83%,about 1.84%, about 1.85%, about 1.86%, about 1.87%, about 1.88%, about1.89%, about 1.9%, about 1.91%, about 1.92%, about 1.93%, about 1.94%,about 1.95%, about 1.96%, about 1.97%, about 1.98%, about 1.99%, about2.0%, about 2.01%, about 2.02%, about 2.03%, about 2.04%, about 2.05%,about 2.06%, about 2.07%, about 2.08%, about 2.09%, about 2.1%, about2.11%, about 2.12%, about 2.13%, about 2.14%, about 2.15%, about 2.16%,about 2.17%, about 2.18%, about 2.19%, about 2.2%, about 2.21%, about2.22%, about 2.23%, about 2.24%, about 2.25%, about 2.26%, about 2.27%,about 2.28%, about 2.29%, about 2.3%, about 2.31%, about 2.32%, about2.33%, about 2.34%, about 2.35%, about 2.36%, about 2.37%, about 2.38%,about 2.39%, about 2.4%, about 2.41%, about 2.42%, about 2.43%, about2.44%, about 2.45%, about 2.46%, about 2.47%, about 2.48%, about 2.49%,about 2.5%, 2.51%, about 2.52%, about 2.53%, about 2.54%, about 2.55%,about 2.56%, about 2.57%, about 2.58%, about 2.59%, about 2.6%, about2.61%, about 2.62%, about 2.63%, about 2.64%, about 2.65%, about 2.66%,about 2.67%, about 2.68%, about 2.69%, about 2.7%, about 2.71%, about2.72%, about 2.73%, about 2.74%, about 2.75%, about 2.76%, about 2.77%,about 2.78%, about 2.79%, about 2.8%, about 2.81%, about 2.82%, about2.83%, about 2.84%, about 2.85%, about 2.86%, about 2.87%, about 2.88%,about 2.89%, about 2.9%, about 2.91%, about 2.92%, about 2.93%, about2.94%, about 2.95%, about 2.96%, about 2.97%, about 2.98%, about 2.99%,or about 3.0% Zn. All percentages are expressed in wt. %. The zinccontent can improve the corrosion resistance of the aluminum alloysdescribed herein. Specifically, when zinc is incorporated at a level asdescribed herein, such as from 1.0% to 2.6%, the alloys exhibit enhancedcorrosion resistance as compared to fin stock typically used inindustrial processes (e.g., 1xxx series and 7xxx series alloys). In somefurther examples, Zn can decrease resistance to corrosion whenincorporated at weight percentages exceeding those described herein. Instill further examples, Zn can be incorporated in an aluminum alloy inan optimal amount, as described herein, to provide an alloy suitable foruse as an industrial fin. For example, at Zn levels higher than thosedescribed herein, the alloys for use as fins can corrode more rapidlythan for fins containing the described amount of Zn, resulting inperforations in the fin. As a result, the mechanical integrity andthermal performance of the heat exchanger can be compromised, thusaffecting the service life of the heat exchanger.

In some examples, the disclosed alloy includes silicon (Si) in an amountfrom about 0.15% to about 0.35% (e.g., from about 0.20% to about 0.35%,from about 0.17% to about 0.33%, or from about 0.20% to about 0.33%)based on the total weight of the alloy. For example, the alloy caninclude about 0.15%, about 0.16%, about 0.17%, about 0.18%, about 0.19%,about 0.2%, about 0.21%, about 0.22%, about 0.23%, about 0.24%, about0.25%, about 0.26%, about 0.27%, about 0.28%, about 0.29%, about 0.30%,about 0.31%, about 0.32%, about 0.33%, about 0.34%, or about 0.35% Si.All percentages are expressed in wt. %.

In some examples, the alloy also includes iron (Fe) in an amount fromabout 0.25% to about 0.65% (e.g., from 0.35% to about 0.60%, from 0.30%to 0.55%, or from 0.49% to 0.6%) based on the total weight of the alloy.For example, the alloy can include about 0.25%, about 0.26%, about0.27%, about 0.28%, about 0.29%, about 0.3%, about 0.31%, about 0.32%,about 0.33%, about 0.34%, about 0.35%, about 0.36%, about 0.37%, about0.38%, about 0.39%, about 0.4%, about 0.41%, about 0.42%, about 0.43%,about 0.44%, about 0.45%, about 0.46%, about 0.47%, about 0.48%, about0.49%, about 0.5%, about 0.51%, about 0.52%, about 0.53%, about 0.54%,about 0.55%, about 0.56%, about 0.57%, about 0.58%, about 0.59%, about0.6%, about 0.61%, about 0.62%, about 0.63%, about 0.64%, or about 0.65%Fe. All percentages are expressed in wt. %.

In some examples, the disclosed alloy includes copper (Cu) in an amountfrom about 0.05% to about 0.20% (e.g., from about 0.10% to about 0.20%,from about 0.15% to about 0.20%, or from about 0.15% to about 0.19%)based on the total weight of the alloy. For example, the alloy caninclude about 0.05%, about 0.06%, about 0.07%, about 0.08%, about 0.09%,about 0.1%, about 0.11%, about 0.12%, about 0.13%, about 0.14%, about0.15%, about 0.16%, about 0.17%, about 0.18%, about 0.19%, or about 0.2%Cu. All percentages are expressed in wt. %.

In some examples, the alloy can include manganese (Mn) in an amount fromabout 0.75% to about 1.5% (e.g., from about 0.75% to about 1.25%, fromabout 0.80% to about 1.00%, or from about 0.79% to about 0.94%) based onthe total weight of the alloy. For example, the alloy can include about0.75%, about 0.76%, about 0.77%, about 0.78%, about 0.79%, about 0.8%,about 0.81%, about 0.82%, about 0.83%, about 0.84%, about 0.85%, about0.86%, about 0.87%, about 0.88%, about 0.89%, about 0.9%, about 0.91%,about 0.92%, about 0.93%, about 0.94%, about 0.95%, about 0.96%, about0.97%, about 0.98%, about 0.99%, about 1.0%, about 1.01%, about 1.02%,about 1.03%, about 1.04%, about 1.05%, about 1.06%, about 1.07%, about1.08%, about 1.09%, about 1.1%, about 1.11%, about 1.12%, about 1.13%,about 1.14%, about 1.15%, about 1.16%, about 1.17%, about 1.18%, about1.19%, about 1.2%, about 1.21%, about 1.22%, about 1.23%, about 1.24%,about 1.25%, about 1.26%, about 1.27%, about 1.28%, about 1.29%, about1.3%, about 1.31%, about 1.32%, about 1.33%, about 1.34%, about 1.35%,about 1.36%, about 1.37%, about 1.38%, about 1.39%, about 1.4%, about1.41%, about 1.42%, about 1.43%, about 1.44%, about 1.45%, about 1.46%,about 1.47%, about 1.48%, about 1.49%, or 1.5% Mn. All percentages areexpressed in wt. %.

In some examples, the alloy can include magnesium (Mg) in an amount fromabout 0.50% to about 1.50% (e.g., from about 0.90% to about 1.30%, fromabout 1.00% to about 1.25%, or from about 1.13% to about 1.27%) based onthe total weight of the alloy. For example, the alloy can include about0.5%, about 0.51%, about 0.52%, about 0.53%, about 0.54%, about 0.55%,about 0.56%, about 0.57%, about 0.58%, about 0.59%, about 0.6%, about0.61%, about 0.62%, about 0.63%, about 0.64%, about 0.65%, about 0.66%,about 0.67%, about 0.68%, about 0.69%, about 0.7%, about 0.71%, about0.72%, about 0.73%, about 0.74%, about 0.75%, about 0.76%, about 0.77%,about 0.78%, about 0.79%, about 0.8%, about 0.81%, about 0.82%, about0.83%, about 0.84%, about 0.85%, about 0.86%, about 0.87%, about 0.88%,about 0.89%, about 0.9%, about 0.91%, about 0.92%, about 0.93%, about0.94%, about 0.95%, about 0.96%, about 0.97%, about 0.98%, about 0.99%,about 1.0%, about 1.01%, about 1.02%, about 1.03%, about 1.04%, about1.05%, about 1.06%, about 1.07%, about 1.08%, about 1.09%, about 1.1%,about 1.11%, about 1.12%, about 1.13%, about 1.14%, about 1.15%, about1.16%, about 1.17%, about 1.18%, about 1.19%, about 1.2%, about 1.21%,about 1.22%, about 1.23%, about 1.24%, about 1.25%, about 1.26%, about1.27%, about 1.28%, about 1.29%, about 1.3%, about 1.31%, about 1.32%,about 1.33%, about 1.34%, about 1.35%, about 1.36%, about 1.37%, about1.38%, about 1.39%, about 1.4%, about 1.41%, about 1.42%, about 1.43%,about 1.44%, about 1.45%, about 1.46%, about 1.47%, about 1.48%, about1.49%, or 1.5% Mg. All percentages are expressed in wt. %.

In some examples, the alloy includes chromium (Cr) in an amount up toabout 0.10% (e.g., from 0% to about 0.05%, from about 0.001% to about0.04%, or from about 0.01% to about 0.03%) based on the total weight ofthe alloy. For example, the alloy can include about 0.001%, about0.002%, about 0.003%, about 0.004%, about 0.005%, about 0.006%, about0.007%, about 0.008%, about 0.009%, about 0.01%, about 0.02%, about0.03%, about 0.04%, about 0.05%, about 0.06%, about 0.07%, about 0.08%,about 0.09%, or about 0.1% Cr. In some cases, Cr is not present in thealloy (i.e., 0%). All percentages are expressed in wt. %.

In some examples, the alloy includes titanium (Ti) in an amount up toabout 0.10% (e.g., from 0% to about 0.05%, from about 0.001% to about0.04%, or from about 0.01% to about 0.03%) based on the total weight ofthe alloy. For example, the alloy can include about 0.001%, about0.002%, about 0.003%, about 0.004%, about 0.005%, about 0.006%, about0.007%, about 0.008%, about 0.009%, about 0.01%, about 0.02%, about0.03%, about 0.04%, about 0.05%, about 0.06%, about 0.07%, about 0.08%,about 0.09%, or about 0.1% Ti. In some cases, Ti is not present in thealloy (i.e., 0%). All percentages are expressed in wt. %.

Optionally, the alloy compositions can further include other minorelements, sometimes referred to as impurities, in amounts of about 0.05%or below, 0.04% or below, 0.03% or below, 0.02% or below, or 0.01% orbelow each. These impurities may include, but are not limited to, Ga, V,Ni, Sc, Ag, B, Bi, Zr, Li, Pb, Sn, Ca, Hf, Sr, or combinations thereof.Accordingly, Ga, V, Ni, Sc, Ag, B, Bi, Zr, Li, Pb, Sn, Ca, Hf, or Sr maybe present in an alloy in amounts of 0.05% or below, 0.04% or below,0.03% or below, 0.02% or below, or 0.01% or below. In certain aspects,the sum of all impurities does not exceed 0.15% (e.g., 0.1%). Allpercentages are expressed in wt. %. In certain aspects, the remainingpercentage of the alloy is aluminum.

Optionally, exemplary aluminum alloys as described herein can includeabout 0.9-2.6% Zn (e.g., about 1.4-1.6% Zn), about 0.2-0.33% Si, about0.49-0.6% Fe, about 0.15-0.19% Cu, about 0.79-0.94% Mn, about 1.13-1.27%Mg, up to about 0.05% Cr, up to about 0.05% Ti, and up to about 0.15% ofimpurities, with the remainder as Al. For example, an exemplary alloyincludes 1.53% Zn, 0.3% Si, 0.51% Fe, 0.17% Cu, 0.87% Mn, 1.21% Mg,0.001% Cr, 0.016% Ti, and up to 0.15% total impurities, with theremainder as Al. In some examples, an exemplary alloy includes 1.00% Zn,0.29% Si, 0.51% Fe, 0.16% Cu, 0.86% Mn, 1.2% Mg, 0.001% Cr, 0.011% Ti,and up to 0.15% total impurities, with the remainder as Al. In someexamples, an exemplary alloy includes 2.04% Zn, 0.29% Si, 0.51% Fe,0.17% Cu, 0.87% Mn, 1.21% Mg, 0.001% Cr, 0.015% Ti, and up to 0.15%total impurities, with the remainder as Al. In some examples, anexemplary alloy includes 2.54% Zn, 0.29% Si, 0.51% Fe, 0.17% Cu, 0.88%Mn, 1.23% Mg, 0.001% Cr, 0.012% Ti, and up to 0.15% total impurities,with the remainder as Al.

Alloy Properties

The mechanical properties of the aluminum alloy can be controlled byvarious processing conditions depending on the desired use. The alloycan be produced (or provided) in an H temper (e.g., HX1, HX2, HX3 HX4,HX5, HX6, HX7, HX8, or HX9 tempers). As one example, the alloy can beproduced (or provided) in the H19 temper. H19 temper refers to productsthat are cold rolled. As another example, the alloy can be produced (orprovided) in the H23 temper. H23 temper refers to products that are coldrolled and partially annealed. As a further example, the alloy can beproduced (or provided) in the O temper. O temper refers to products thatare cold rolled and fully annealed.

In some non-limiting examples, the disclosed alloys have high strengthin the H tempers (e.g., H19 temper and H23 temper) and high formability(i.e., bendability) in the O temper. In some non-limiting examples, thedisclosed alloys have good corrosion resistance in the H tempers (e.g.,H19 temper and H23 temper), and O temper compared to conventional 7xxxand 1xxx series aluminum alloys employed as industrial fin stock.

In certain aspects, the aluminum alloys can have a yield strength (YS)of at least about 70 MPa. In non-limiting examples, the yield strengthis at least about 70 MPa, at least about 80 MPa, at least about 90 MPa,at least about 100 MPa, at least about 110 MPa, at least about 120 MPa,at least about 130 MPa, at least about 140 MPa, at least about 150 MPa,at least about 160 MPa, at least about 170 MPa, at least about 180 MPa,at least about 190 MPa, at least about 200 MPa, at least about 210 MPa,at least about 220 MPa, at least about 230 MPa, at least about 240 MPa,at least about 250 MPa, at least about 260 MPa, at least about 270 MPa,at least about 280 MPa, at least about 290 MPa, at least about 300 MPa,at least about 310 MPa, at least about 320 MPa, at least about 330 MPa,at least about 340 MPa, at least about 350 MPa, or anywhere in between.In some cases, the yield strength is from about 70 MPa to about 350 MPa.For example, the yield strength can be from about 80 MPa to about 340MPa, from about 90 MPa to about 320 MPa, from about 100 MPa to about 300MPa, from about 180 MPa to about 300 MPa, or from about 200 MPa to about300 MPa.

The yield strength will vary based on the tempers of the alloys. In someexamples, the alloys described herein provided in an O temper can have ayield strength of from at least about 70 MPa to about 200 MPa. Innon-limiting examples, the yield strength of the alloys in O temper isat least about 70 MPa, at least about 80 MPa, at least about 90 MPa, atleast about 100 MPa, at least about 110 MPa, at least about 120 MPa, atleast about 130 MPa, at least about 140 MPa, at least about 150 MPa, atleast about 160 MPa, at least about 170 MPa, at least about 180 MPa, atleast about 190 MPa, at least about 200 MPa, or anywhere in between.

In some further examples, the alloys described herein in an H temper canhave a yield strength of at least about 200 MPa, at least about 210 MPa,at least about 220 MPa, at least about 230 MPa, at least about 240 MPa,at least about 250 MPa, at least about 260 MPa, at least about 270 MPa,at least about 280 MPa, at least about 290 MPa, at least about 300 MPa,at least about 310 MPa, at least about 320 MPa, at least about 330 MPa,at least about 340 MPa, at least about 350 MPa, or anywhere in between.

In certain aspects, the aluminum alloys can have an ultimate tensilestrength (UTS) of at least about 170 MPa. In non-limiting examples, theUTS is at least about 170 MPa, at least about 180 MPa, at least about190 MPa, at least about 200 MPa, at least about 210 MPa, at least about220 MPa, at least about 230 MPa, at least about 240 MPa, at least about250 MPa, at least about 260 MPa, at least about 270 MPa, at least about280 MPa, at least about 290 MPa, at least about 300 MPa, at least about310 MPa, at least about 320 MPa, at least about 330 MPa, at least about340 MPa, at least about 350 MPa, or anywhere in between. In some cases,the UTS is from about 200 MPa to about 320 MPa. For example, the UTS canbe from about 200 MPa to about 320 MPa, from about 190 MPa to about 290MPa, from about 300 MPa to about 350 MPa, from about 180 MPa to about340 MPa, or from about 175 MPa to about 325 MPa.

In some examples, the alloys described herein provided in an O tempercan have an UTS of from at least about 170 MPa to about 250 MPa. Innon-limiting examples, the UTS of the alloys in O temper is at leastabout 170 MPa, at least about 180 MPa, at least about 190 MPa, at leastabout 200 MPa, at least about 210 MPa, at least about 220 MPa, at leastabout 230 MPa, at least about 240 MPa, at least about 250 MPa, oranywhere in between.

In some further examples, the alloys described herein in an H temper canhave an UTS of at least about 200 MPa, at least about 210 MPa, at leastabout 220 MPa, at least about 230 MPa, at least about 240 MPa, at leastabout 250 MPa, at least about 260 MPa, at least about 270 MPa, at leastabout 280 MPa, at least about 290 MPa, at least about 300 MPa, at leastabout 310 MPa, at least about 320 MPa, at least about 330 MPa, at leastabout 340 MPa, at least about 350 MPa, or anywhere in between.

In certain aspects, the alloy encompasses any yield strength that hassufficient formability to meet an elongation of about 9.75% or greaterin the O temper (e.g., about 10.0% or greater). In certain examples, theelongation can be about 9.75% or greater, about 10.0% or greater, about10.25% or greater, about 10.5% or greater, about 10.75% or greater,about 11.0% or greater, about 11.25% or greater, about 11.5% or greater,about 11.75% or greater, about 12.0% or greater, about 12.25% orgreater, about 12.5% or greater, about 12.75% or greater, about 13.0% orgreater, about 13.25% or greater, about 13.5% or greater, about 13.75%or greater, about 14.0% or greater, about 14.25% or greater, about 14.5%or greater, about 14.75 or greater, about 15.0% or greater, about 15.25%or greater, about 15.5% or greater, about 15.75% or greater, about 16.0%or greater, about 16.25% or greater, about 16.5% or greater, or anywherein between.

In certain aspects, the alloy can have a corrosion resistance thatprovides a negative corrosion potential or electrochemical potential(Ecorr) of about −700 mV or less when tested according to the ASTM G69standard. In certain cases, an open corrosion potential value vs.Standard Calomel Electrode (SCE) can be about −700 mV or less, about−710 mV or less, about −720 mV or less, about −730 mV or less, about−740 mV or less, about −750 mV or less, about −760 mV or less, about−770 mV or less, about −780 mV or less, about −790 mV or less, about−800 mV or less, about −810 mV or less, about −820 mV or less, about−830 mV or less, about −840 mV or less, about −850 mV or less, oranywhere in between. For example, the aluminum alloy can have an opencorrosion potential of from about −740 mV to about −850 mV (e.g., fromabout −750 mV to about −840 mV or from about −770 mV to about −830 mV).

In some examples, the alloy can have an average conductivity value ofabove about 36% based on the international annealed copper standard(IACS) (e.g., from about 37% IACS to about 44% IACS). For example, thealloy can have an average conductivity value of about 37%, about 38%,about 39%, about 40%, about 41%, about 42%, about 43%, about 44%, oranywhere in between. All values in % IACS.

Methods of Preparing and Processing

In certain aspects, the disclosed alloy composition is a product of adisclosed method. Without intending to limit the disclosure, aluminumalloy properties are partially determined by the formation ofmicrostructures during the alloy's preparation. In certain aspects, themethod of preparation for an alloy composition may influence or evendetermine whether the alloy will have properties adequate for a desiredapplication.

Casting

The alloy described herein can be cast using a casting method as knownto those of skill in the art. For example, the casting process caninclude a Direct Chill (DC) casting process. The DC casting process isperformed according to standards commonly used in the aluminum industryas known to one of skill in the art. The DC process can provide aningot. Optionally, the ingot can be scalped before downstreamprocessing. Optionally, the casting process can include a continuouscasting (CC) process.

The cast aluminum alloy can then be subjected to further processingsteps. For example, the processing methods as described herein caninclude the steps of homogenization, hot rolling, cold rolling, and/orannealing.

Homogenization

The homogenization step can include heating a cast aluminum alloy asdescribed herein to attain a homogenization temperature of about, or atleast about, 570° C. (e.g., at least about 570° C., at least about 580°C., at least about 590° C., at least about 600° C., at least about 610°C., or anywhere in between). For example, the cast aluminum alloy can beheated to a temperature of from about 570° C. to about 620° C., fromabout 575° C. to about 615° C., from about 585° C. to about 610° C., orfrom about 590° C. to about 605° C. In some cases, the heating rate tothe homogenization temperature can be about 100° C./hour or less, about75° C./hour or less, about 50° C./hour or less, about 40° C./hour orless, about 30° C./hour or less, about 25° C./hour or less, about 20°C./hour or less, about 15° C./hour or less, or about 10° C./hour orless. In other cases, the heating rate to the homogenization temperaturecan be from about 10° C./min to about 100° C./min (e.g., about 10°C./min to about 90° C./min, about 10° C./min to about 70° C./min, about10° C./min to about 60° C./min, from about 20° C./min to about 90°C./min, from about 30° C./min to about 80° C./min, from about 40° C./minto about 70° C./min, or from about 50° C./min to about 60° C./min).

The cast aluminum alloy is then allowed to soak (i.e., held at theindicated temperature) for a period of time. According to onenon-limiting example, the cast aluminum alloy is allowed to soak for upto about 5 hours (e.g., from about 10 minutes to about 5 hours,inclusively). For example, the cast aluminum alloy can be soaked at atemperature of at least 570° C. for 10 minutes, 20 minutes, 30 minutes,1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or anywhere in between.

The cast aluminum alloy can be cooled from the first temperature to asecond temperature that is lower than the first temperature. In someexamples, the second temperature is greater than about 555° C. (e.g.,greater than about 560° C., greater than about 565° C., greater thanabout 570° C., or greater than about 575° C.). For example, the castaluminum alloy can be cooled to a second temperature of from about 555°C. to about 590° C., from about 560° C. to about 575° C., from about565° C. to about 580° C., from about 570° C. to about 585° C., fromabout 565° C. to about 570° C., from about 570° C. to about 590° C., orfrom about 575° C. to about 585° C. The cooling rate to the secondtemperature can be from about 10° C./min to about 100° C./min (e.g.,from about 20° C./min to about 90° C./min, from about 30° C./min toabout 80° C./min, from about 10° C./min to about 90° C./min, from about10° C./min to about 70° C./min, from about 10° C./min to about 60°C./min, from about 40° C./min to about 70° C./min, or from about 50°C./min to about 60° C./min).

The cast aluminum alloy can then be allowed to soak at the secondtemperature for a period of time. In certain cases, the ingot is allowedto soak for up to about 5 hours (e.g., from 10 minutes to 5 hours,inclusively). For example, the ingot can be soaked at a temperature offrom about 560° C. to about 590° C. for 10 minutes, 20 minutes, 30minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or anywhere inbetween.

Hot Rolling

Following the homogenization step, a hot rolling step can be performed.In certain cases, the cast aluminum alloys are hot-rolled with a hotmill entry temperature range of about 560° C. to about 600° C. Forexample, the entry temperature can be about 560° C., about 565° C.,about 570° C., about 575° C., about 580° C., about 585° C., about 590°C., about 595° C., or about 600° C. In certain cases, the hot roll exittemperature can range from about 290° C. to about 350° C. (e.g., fromabout 310° C. to about 340° C.). For example, the hot roll exittemperature can be about 290° C., about 295° C., about 300° C., about305° C., about 310° C., about 315° C., about 320° C., about 325° C.,about 330° C., about 335° C., about 340° C., about 345° C., about 350°C., or anywhere in between.

In certain cases, the cast aluminum alloy can be hot rolled to an about2 mm to about 15 mm thick gauge (e.g., from about 2.5 mm to about 12 mmthick gauge). For example, the cast aluminum alloy can be hot rolled toan about 2 mm thick gauge, about 2.5 mm thick gauge, about 3 mm thickgauge, about 3.5 mm thick gauge, about 4 mm thick gauge, about 5 mmthick gauge, about 6 mm thick gauge, about 7 mm thick gauge, about 8 mmthick gauge, about 9 mm thick gauge, about 10 mm thick gauge, about 11mm thick gauge, about 12 mm thick gauge, about 13 mm thick gauge, about14 mm thick gauge, or about 15 mm thick gauge. In certain cases, thecast aluminum alloy can be hot rolled to a gauge greater than 15 mm(i.e., a plate). In other cases, the cast aluminum alloy can be hotrolled to a gauge less than 4 mm (i.e., a sheet).

Cold Rolling

A cold rolling step can be performed following the hot rolling step. Incertain aspects, the rolled product from the hot rolling step can becold rolled to a sheet (e.g., below approximately 4.0 mm). In certainaspects, the rolled product is cold rolled to a thickness of about 0.4mm to about 1.0 mm, about 1.0 mm to about 3.0 mm, or about 3.0 mm toless than about 4.0 mm. In certain aspects, the alloy is cold rolled toabout 3.5 mm or less, about 3 mm or less, about 2.5 mm or less, about 2mm or less, about 1.5 mm or less, about 1 mm or less, about 0.5 mm orless, about 0.4 mm or less, about 0.3 mm or less, about 0.2 mm or less,or about 0.1 mm or less. For example, the rolled product can be coldrolled to about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about1.0 mm, about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, about1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, about2.0 mm, about 2.1 mm, about 2.2 mm, about 2.3 mm, about 2.4 mm, about2.5 mm, about 2.6 mm, about 2.7 mm, about 2.8 mm, about 2.9 mm, about3.0 mm, about 3.1 mm, about 3.2 mm, about 3.3 mm, about 3.4 mm, about3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8 mm, about 3.9 mm, about4.0 mm, or anywhere in between.

In one case, the method for processing the aluminum alloys as describedherein can include the following steps. A homogenization step can beperformed by heating a cast aluminum alloy as described herein to attaina homogenization temperature of about 590° C. over a time period ofabout 12 hours, wherein the cast aluminum alloys are allowed to soak ata temperature of about 590° C. for about 2 hours. The cast aluminumalloys can then be cooled to about 580° C. and allowed to soak for about2 hours at 580° C. The cast aluminum alloys can then be hot rolled to agauge of about 2.5 mm thick. The cast aluminum alloys can then be coldrolled to a gauge of less than about 1.0 mm thick (e.g., about 1.0 mm orless or about 0.15 mm or less), providing an aluminum alloy sheet.

Annealing

Optionally, the aluminum alloy sheet can be annealed by heating thesheet from room temperature to an annealing temperature of from about200° C. to about 400° C. (e.g., from about 210° C. to about 375° C.,from about 220° C. to about 350° C., from about 225° C. to about 345°C., or from about 250° C. to about 320° C.). In some cases, the heatingrate to the annealing temperature can be about 100° C./hour or less,about 75° C./hour or less, about 50° C./hour or less, about 40° C./houror less, about 30° C./hour or less, about 25° C./hour or less, about 20°C./hour or less, about 15° C./hour or less, or about 10° C./hour orless. The sheet can soak at the temperature for a period of time. Incertain aspects, the sheet is allowed to soak for up to approximately 6hours (e.g., from about 10 seconds to about 6 hours, inclusively). Forexample, the sheet can be soaked at the temperature of from about 230°C. to about 370° C. for about 20 seconds, about 25 seconds, about 30seconds, about 35 seconds, about 40 seconds, about 45 seconds, about 50seconds, about 55 seconds, about 60 seconds, about 65 seconds, about 70seconds, about 75 seconds, about 80 seconds, about 85 seconds, about 90seconds, about 95 seconds, about 100 seconds, about 105 seconds, about110 seconds, about 115 seconds, about 120 seconds, about 125 seconds,about 130 seconds, about 135 seconds, about 140 seconds, about 145seconds, about 150 seconds, about 5 minutes, about 10 minutes, about 15minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55minutes, about 60 minutes, about 65 minutes, about 70 minutes, about 75minutes, about 80 minutes, about 85 minutes, about 90 minutes, about 95minutes, about 100 minutes, about 105 minutes, about 110 minutes, about115 minutes, about 120 minutes, about 2.5 hours, about 3 hours, about3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5hours, about 6 hours, or anywhere in between. In some examples, thesheet is not annealed.

In some examples, the sheet is heated to an annealing temperature ofabout 200° C. to about 400° C. at a constant rate of about 40° C./hourto about 50° C./hour. In some aspects, the sheet is allowed to soak atthe annealing temperature for about 3 hours to about 5 hours (e.g., forabout 4 hours). In some cases, the sheet is cooled from the annealingtemperature at a constant rate of about 40° C./hour to about 50°C./hour. In some examples, the sheet is not annealed.

Methods of Using

The alloys and methods described herein can be used in industrialapplications including sacrificial parts, heat dissipation, packaging,and building materials. The alloys described herein can be employed asindustrial fin stock for heat exchangers. The industrial fin stock canbe provided such that it is more resistant to corrosion than currentlyemployed industrial fin stock alloys (e.g., AA7072 and AA1100) and willstill preferentially corrode protecting other metal parts incorporatedin a heat exchanger. The aluminum alloys disclosed herein are suitablesubstitutes for metals conventionally used in indoor and outdoor HVACunits. As used herein, the meaning of “indoor” refers to a placementcontained within any structure produced by humans with controlledenvironmental conditions. As used herein, the meaning of “outdoor”refers to a placement not fully contained within any structure producedby humans and exposed to geological and meteorological environmentalconditions comprising air, solar radiation, wind, rain, sleet, snow,freezing rain, ice, hail, dust storms, humidity, aridity, smoke (e.g.,tobacco smoke, house fire smoke, industrial incinerator smoke and wildfire smoke), smog, fossil fuel exhaust, bio-fuel exhaust, salts (e.g.,high salt content air in regions near a body of salt water),radioactivity, electromagnetic waves, corrosive gases, corrosiveliquids, galvanic metals, galvanic alloys, corrosive solids, plasma,fire, electrostatic discharge (e.g., lightning), biological materials(e.g., animal waste, saliva, excreted oils, vegetation), wind-blownparticulates, barometric pressure change, and diurnal temperaturechange. The aluminum alloys described herein provide better corrosionperformance and higher strength as compared to alloys currentlyemployed.

The following examples will serve to further illustrate the presentinvention without, however, constituting any limitation thereof. On thecontrary, it is to be clearly understood that resort may be had tovarious embodiments, modifications and equivalents thereof which, afterreading the description herein, may suggest themselves to those skilledin the art without departing from the spirit of the invention. Duringthe studies described in the following examples, conventional procedureswere followed, unless otherwise stated. Some of the procedures aredescribed below for illustrative purposes.

EXAMPLES Example 1: Mechanical Properties

Exemplary and comparative alloys, as shown in Table 5, were preparedaccording to the methods described herein. Alloys 1, 2, 3, and 4 areexemplary alloys created according to methods described herein. Alloy 5is a comparative alloy prepared according to methods described herein.Alloy A is AA7072, which is currently employed as an industrial finstock in commercial applications. Alloy B is AA1100, which is currentlyemployed as an industrial fin stock in commercial applications.

TABLE 5 Alloy Zn Si Fe Cu Mn Mg Cr Ti 1 1.00 0.29 0.51 0.16 0.86 1.20.001 0.011 2 1.53 0.3 0.51 0.17 0.87 1.21 0.001 0.016 3 2.04 0.29 0.510.17 0.87 1.21 0.001 0.015 4 2.54 0.29 0.51 0.17 0.88 1.23 0.001 0.012 50.15 0.22 0.31 0.07 1.00 1.02 0.001 0.16 Comp. A 1.3 0.07 0.37 0.01 0.030.03 0.02 0.03 Comp. B 0.1 0.165 0.55 0.075 0.02 0.01 0.02 0.03 Allexpressed as wt. %.

The mechanical properties of the exemplary alloys and comparative alloyswere determined according to ASTM B557. Specifically, the alloys weresubjected to tensile, elongation, and conductivity tests. The yieldstrength (YS), ultimate tensile strength (UTS), percent elongation (EI),and percent of the International Annealed Copper Standard (% IACS) weredetermined. The test results are summarized in Table 6.

TABLE 6 YS UTS El YS UTS El YS UTS El Gauge (MPa) (MPa) (%) % IACS (MPa)(MPa) (%) % IACS (MPa) (MPa) (%) % IACS Alloy (mm) H19 H23 O 1 0.155 289296 1.77 39.6 210 241 6.94 41.6 67 171 16.38 42.0 2 0.161 299 307 2.3742.6 207 239 7.09 41.7 109 183 12.93 43.6 3 0.156 300 308 2.18 40.8 206236 6.99 41.7 78 190 13.63 39.2 4 0.160 309 318 2.14 40.7 212 240 6.4641.7 85 205 14.31 43.8 5 0.152 289 297 1.98 36.0 204 230 5.58 36.6 160206 9.78 39.1 Comp. 0.178 196 213 5.1 59 — — — — — — — — A Comp. 0.102 —— — — 108 122.0 20.4 60.3 — — — — B* *Comp. B temper was in H22 temperduring testing.

Evident in the tensile test results is the excellent strength of theexemplary alloys compared to alloys currently employed as industrial finstock. The exemplary alloys exhibited an average conductivity of about37-44% IACS. As shown above in Table 6, the exemplary alloys describedherein display exceptional mechanical properties as compared to thecomparative alloys and can be excellent commercial alloys employed inindustrial fin stock applications.

Example 2: Corrosion Properties

The corrosion properties of exemplary alloys described herein andcomparative alloys described herein, elemental compositions of which areprovided in Table 5, were determined. In addition, the corrosionproperties of two additional comparative tube alloys were determined.Comp. Alloy C is an aluminum tube alloy containing 0.15 wt. % Zn andComp. Alloy D is an AA1235 aluminum alloy commonly used in heatexchangers. The open circuit potential corrosion values were measuredaccording to ASTM G69. Corrosion test results are summarized in Table 7.The aluminum tube alloys Comp. Alloy C and Comp. Alloy D had an averageopen corrosion potential value vs. SCE of −741 mV.

TABLE 7 Zn Ecorr(mV) vs. SCE Alloy (wt. %) H19 H23 O 1 1.00 −747 −749−739 2 1.53 −778 −759 −779 3 2.04 −792 −761 −794 4 2.54 −809 −766 −821 50.15 −731 −730 −730 Comp. A 1.30 −886 — — Comp. B* 0.10 — −731 — Comp. C−741 Comp. D −742 *Alloy AA1100 temper was in H22 temper during testing.

The differences in corrosion resistance values between Alloys 1-5 andComp. Alloy C are shown below in Table 8.

TABLE 8 Zn ΔEcorr(mV) Alloy (wt. %) H19 H23 O 1 1.00 6 8 −2 2 1.53 37 1838 3 2.04 51 20 53 4 2.54 68 25 80 5 0.15 −10 −11 −11

The differences in corrosion resistance values between Alloys 1-5 andComp. Alloy D are shown below in Table 9.

TABLE 9 Zn ΔEcorr(mV) Alloy (wt. %) H19 H23 O 1 1.00 5 7 −3 2 1.53 36 1737 3 2.04 50 19 52 4 2.54 67 24 79 5 0.15 −11 −12 −12

The exemplary alloys in all tempers (e.g., H19, H23, and O) exhibitedelectrochemical potential values comparable to the comparative alloys.The differences between Alloys 1-5 and Comp. Alloy C and between Alloys1-5 and Comp. Alloy D ranged from 15-80 mV. The data show that Alloys 2,3, 4 and 5 are acceptable to prepare fins that act as sacrificialanodes.

Exemplary alloys with varying Zn subjected to electrochemical corrosiontesting also exhibited a nearly linear correlation between Zn contentand electrochemical potential. On average, an increase of 0.1 wt. % Znprovided an increase of about 9 mV in electrochemical potential.Exemplary alloys with a Zn content of about 2.5 wt. % or greaterexhibited more negative corrosion potential, indicating thatincorporating Zn greater than about 2.5 wt. % may not be desirable forachieving certain properties. Zn can be added optimally to besufficiently resistant to corrosion to serve as a sacrificial alloy in aheat exchanger yet still preferentially corrode ahead of any primaryfunctional metal parts of a heat exchanger, further suggesting theexemplary alloys described herein are excellent replacements forcurrently employed alloys used in industrial fin stock.

The corrosion properties of the exemplary alloys described herein andthe comparative alloys described herein according to ASTM G71 were alsodetermined. Specifically, the corrosion properties were measured usingzero resistance ammetry (ZRA). The ZRA galvanic compatibility wasmeasured where the exemplary alloys were used as fin stock and Comp.Alloy C and Comp. Alloy D were used as tubestock. The results shown inTables 10 and 11 represent the average current for the last four hoursof the cycle as performed according to the test method. Table 10 showsthe ZRA results for Alloys 1-5 galvanically coupled to Comp. Alloy C.

TABLE 10 Zn Average Current (μA/cm²) Alloy (wt. %) H19 H23 1 1.00 26 352 1.53 29 24 3 2.04 30 37 4 2.54 27 26 5 0.15 −23 −15

As shown in Table 10, Alloys 1, 2, 3, and 4, containing from 1 to 2.5wt. % Zn, displayed a positive corrosion current indicating that theexemplary fin alloys provided sacrificial protection to the tube alloys.

Table 11 shows the ZRA results for Alloys 1-5 galvanically coupled toComp. Alloy D.

TABLE 11 Zn Average Current (μA/cm²) Alloy (wt. %) H19 H23 1 1.00 −3012.8 2 1.53 10 15 3 2.04 13 4.5 4 2.54 25 9.1 5 0.15 −25 −29

As shown in Table 11, Alloys 1, 2, 3, and 4, containing from 1 to 2.5wt. % Zn, displayed lower corrosion currents than exemplary alloyscoupled with Comp. Alloy C, but still provided sacrificial protection tothe tube alloy. All the exemplary fin alloys showed that a protectivecurrent was being provided to the Comp. Alloy C and Comp. Alloy D tubesthroughout the test period.

The compatibilities of exemplary fin alloys attached to comparative tubealloys Comp. Alloy C and Comp. Alloy D were also evaluated according toASTM G85 Annex 3. Synthetic sea water, acidified to 2.8-3.0 pH, wasused. The exemplary fin samples were mechanically assembled to the tubealloys and subjected to corrosion testing for an exposure of 4 weeks. Asshown in FIGS. 1 and 2, the samples displayed progressively morecorrosion on the exemplary alloys as the zinc content increased from 2%to 2.5%. This is particularly true for the exemplary alloys coupled toComp. Alloy D. Based on these data, Zn levels less than 2 wt. % arepreferred in some instances, but can be optimized depending on tubecomposition.

The aluminum alloys described herein provide sacrificial corrosioncharacteristics and mechanical characteristics which enable themanufacture of aluminum alloy fin stock of reduced metal thickness. Thefin stock of reduced metal thickness maintains sacrificial protectionfor the copper or aluminum alloy tubes in contact with the fins. Thealuminum alloys described herein can also be used in other situationswhere mechanical strength in combination with sacrificialcharacteristics are desired.

All patents, publications and abstracts cited above are incorporatedherein by reference in their entireties. Various embodiments of theinvention have been described in fulfillment of the various objectivesof the invention. It should be recognized that these embodiments aremerely illustrative of the principles of the present invention. Numerousmodifications and adaptions thereof will be readily apparent to thoseskilled in the art without departing from the spirit and scope of thepresent invention as defined in the following claims.

1. An aluminum alloy product, comprising about 0.7-3.0 wt. % Zn, about0.15-0.35 wt. % Si, about 0.25-0.65 wt. % Fe, about 0.05-0.20 wt. % Cu,about 0.75-1.50 wt. % Mn, about 0.60-1.50 wt. % Mg, up to about 0.10 wt.% Cr, up to about 0.10 wt. % Ti, and up to about 0.15 wt. % ofimpurities, with the remainder as Al, wherein the aluminum alloy producthas a gauge of 0.5 mm or less.
 2. The aluminum alloy product of claim 1,comprising about 1.0-2.5 wt. % Zn, about 0.2-0.35 wt. % Si, about0.35-0.60 wt. % Fe, about 0.10-0.20 wt. % Cu, about 0.75-1.25 wt. % Mn,about 0.90-1.30 wt. % Mg, up to about 0.05 wt. % Cr, up to about 0.05wt. % Ti, and up to about 0.15 wt. % of impurities, with the remainderas Al.
 3. The aluminum alloy product of claim 1, comprising about1.5-2.5 wt. % Zn, about 0.17-0.33 wt. % Si, about 0.30-0.55 wt. % Fe,about 0.15-0.20 wt. % Cu, about 0.80-1.00 wt. % Mn, about 1.00-1.25 wt.% Mg, up to about 0.05 wt. % Cr, up to about 0.05 wt. % Ti, and up toabout 0.15 wt. % of impurities, with the remainder as Al.
 4. Thealuminum alloy product of claim 1, comprising about 0.9-2.6 wt. % Zn,about 0.2-0.33 wt. % Si, about 0.49-0.6 wt. % Fe, about 0.15-0.19 wt. %Cu, about 0.79-0.94 wt. % Mn, about 1.13-1.27 wt. % Mg, up to about 0.05wt. % Cr, up to about 0.05 wt. % Ti, and up to about 0.15 wt. % ofimpurities, with the remainder as Al.
 5. The aluminum alloy product ofclaim 1, comprising about 1.4-1.6 wt. % Zn, about 0.2-0.33 wt. % Si,about 0.49-0.6 wt. % Fe, about 0.15-0.19 wt. % Cu, about 0.79-0.94 wt. %Mn, about 1.13-1.27 wt. % Mg, up to about 0.05 wt. % Cr, up to about0.05 wt. % Ti, and up to about 0.15 wt. % of impurities, with theremainder as Al.
 6. The aluminum alloy product of claim 1, wherein thealuminum alloy is produced by direct chill casting or by continuouscasting.
 7. The aluminum alloy product of claim 1, wherein the aluminumalloy is produced by homogenization, hot rolling, cold rolling, andannealing.
 8. The aluminum alloy product of claim 1, wherein thealuminum alloy is in an H temper or an O temper.
 9. The aluminum alloyproduct of claim 1, wherein a yield strength of the aluminum alloy is atleast about 70 MPa.
 10. The aluminum alloy product of claim 1, whereinan ultimate tensile strength of the aluminum alloy is at least about 170MPa.
 11. The aluminum alloy product of claim 1, wherein the aluminumalloy comprises an electrical conductivity above about 37% based on theinternational annealed copper standard (IACS).
 12. The aluminum alloyproduct of claim 1, wherein the aluminum alloy comprises a corrosionpotential of from about −740 mV to about −850 mV.
 13. A fin stockcomprising the aluminum alloy of claim
 1. 14. The fin stock of claim 13,wherein a gauge of the fin stock is 1.0 mm or less.
 15. The fin stock ofclaim 13, wherein a gauge of the fin stock is 0.15 mm or less.
 16. Anarticle comprising a tube and a fin, wherein the fin comprises the finstock according to claim
 13. 17. A method of producing a metal product,comprising: casting an aluminum alloy to form a cast aluminum alloy,wherein the aluminum alloy comprises about 0.7-3.0 wt. % Zn, about0.15-0.35 wt. % Si, about 0.25-0.65 wt. % Fe, about 0.05-0.20 wt. % Cu,about 0.75-1.50 wt. % Mn, about 0.50-1.50 wt. % Mg, up to about 0.05 wt.% Cr, up to about 0.05 wt. % Ti, and up to about 0.15 wt. % ofimpurities, with the remainder as Al; homogenizing the cast aluminumalloy; hot rolling the cast aluminum alloy to produce a rolled product;and cold rolling the rolled product to a final gauge product.
 18. Themethod of claim 17, further comprising annealing the final gaugeproduct. 19-20. (canceled)
 21. The aluminum alloy product of claim 1,wherein the gauge is about 0.2 mm or less.
 22. The aluminum alloyproduct of claim 1, wherein the gauge is about 0.15 mm or less.
 23. Thealuminum alloy product of claim 1, wherein the aluminum alloy product isa heat exchanger fin.